WAEC Physics 2022 Objective — Question 50
Question 50 of 50 from the West African Examinations Council (WAEC) Physics 2022 Objective paper, with the correct answer and a full explanation.
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In which of the following situations is friction not useful?
- A. Operation of a grinding machine
- B. Walking
- C. Application of brakes
- D. Moving piston in a sleeveCorrect
Explanation
Friction between a moving piston and its sleeve is generally undesirable (causing wear and energy loss), unlike friction in grinding, walking, or braking, which is useful.
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